I've been trying to simplify the issue reported in RPR v2.0.32 Uber Shader - Material Assignment *for stickers* - transparency ignored on material assi...
I have come up with the following simple test file (attached) instead.
It demonstrates the issue much better than the linked Community Post Above.
It uses the Alpha channel of the image map file through a Mix Shader.
One input on the Mix shader controls the Decal Material.
The other input on the Mix shader is set to the same Material settings are the rest of the cube.
If the main material of the Cube is refracted in any way the Faces where the Decal material has been assigned will display by stripping away some of the rendering layers (or it changes the refraction... I'm not sure what goes wrong).
However on materials (such as the yellow cube) where the material is not transparent the decal is able to mix in without error.
This should clear up the many versions and test files which were made for the previous post into the core issue, and hopefully make it easier to debug.
Both images below rendered with Blender 2.80 and RPR v2.0.150 on macOS 10.15.0s1 using 2019 MBP i9 with VEGA20 dGPU. (I tested it in B2.81 but the files need the texture map node, so they do not render at all).
I can confirm that this particular bug appears to have been fixed. Thank you.
Another test file that was not working and was the root cause of my original bug report. So I loaded it and it now renders as expected.
Thank you for resolving this issue.